The present invention relates to clutch plates or like torque transmitting devices in general, and more particularly to improvements in torsion damping assemblies which can be utilized in clutch plates of friction clutches for motor vehicles or the like.
It is already known to provide a clutch plate with a torsion damping assembly wherein the input and output components of the clutch plate are angularly movable relative to each other against the opposition of a first damping stage which employs relatively weak energy storing means in the form of coil springs or the like, as well as against the opposition of a second damping stage which operates with stronger energy storing means in the form of coil springs or the like. The relatively weak springs operate between the input and output elements of the first damping stage, and the stronger springs operate between the input and output members of the second damping stage. It is further known to provide the torsion damping assembly with an output component in the form of a hub having internal teeth which can mate with external teeth on the input shaft of a change-speed transmission if the clutch plate is put to use in a friction clutch serving to transmit torque from the internal combustion engine to the change-speed transmission of a motor vehicle. The hub is non-rotatably secured to the output element of the first damping stage and further carries the normally flange-like output member of the second damping stage. As a rule, the flange of the second damping stage has internal teeth which mate, with a certain amount of play, with external teeth on the hub. It is further known to assemble the input component of the clutch plate from two discs which are axially spaced apart from one another and flank the flange (output member) of the main damping stage. Reference may be had, for example, to the published British patent application Ser. No. 2 080 488 of Carray which discloses that the first damping stage is installed at the outer side of one of two discs which constitute the input component of the torsion damping assembly. The mounting of the first damping stage at the outer side of one of the discs is a separate operation which precedes the assembly of the clutch plate. This contributes to the initial cost of the clutch plate, especially since the installation of the first damping stage at the outer side of one disc of the input component necessitates the utilization of a full set of distancing elements for attachment of the first damping stage to the respective disc. Moreover, the space requirements of the torsion damping assembly of Carray are substantial, especially as considered in the axial direction of the clutch plate.
Published French patent application Ser. No. 2 503 295 of Muller discloses a torsion damping assembly wherein the first damping stage is disposed radially inwardly of and is surrounded by the second damping stage, i.e., the two damping stages are in radial alighment with each other. Such torsion damping assemblies are quite bulky (especially as considered in the radial direction of the clutch plate), namely even bulkier than the torsion damping assemblies of the type disclosed by Carray.